Mismatched protagonist duos, anime edition - go!
She’s a bubbly, pink-haired schoolgirl who’s secretly a magical princess from space! He’s a broodingly mysterious white-haired pretty-boy whose cursed blood carries a terrible power! Together… they fight crime!
(I like to imagine that every time he goes off on one of his grandly nihilistic rants, she interrupts him with a well-placed whack upside the head with her sparkly princess wand.)